And if mechanicals, roof, or the electric panel are quite old or appear to be obsolete, just budget on replacing them to keep it simple and conservative.

This can make the building obsolete, like so many golf courses across the country.

Make sure the tenant base isn't going to become obsolete or can't afford raised rents, i.e. exclusively people on fixed income, veterans, etc. • Make sure you can set up a business that relies on algorithms for leasing, to minimize vacancy loss.

Is this home functionally obsolete by today's standards?

From 2007 till about 2010 worked quite well, but when browsers like internet explorer and safari update versions and tweak their code, and your system stays the same; it starts to break, more and more bugs, and soon it becomes obsolete.  

I believe that this system is obsolete and over the years many people have altered the system making it unsafe.

No technology or new industry will ever make real estate obsolete."

however if its in good shape and not functionally obsolete probably 750k to 1 mil.  

Are the traditional methods of raising passive income obsolete thanks to the pandemic?

Thanks :) -Will  I'd never write a mortgage book because it would be obsolete within a year.